code: def pow_minus_1(label: TensorLike) -> tf.Tensor:
      """Computes `2**x - 1` element-wise for each label.
  
      Can be used to define `gain_fn` for `tfr.keras.metrics.NDCGMetric`.
  
      Args:
        label: A `Tensor` or anything that can be converted to a tensor using
          `tf.convert_to_tensor`.
  
      Returns:
        A `Tensor` that has each input element transformed as `x` to `2**x - 1`.
      """
      return tf.math.pow(2.0, label) - 1.0
  
file_path: ranking/tensorflow_ranking/python/keras/utils.py
imports: from typing import Callable
  import tensorflow
label_desc: Use image node_id 5 for calling a global function with example usage: pow_minus_1(label) and returns: unknown